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Basal Ganglia
WVSOM -- Medical Neuroscience -- Basal Ganglia
Question | Answer |
---|---|
What is the function of the basal ganglia? | consultant to the cerebral cortex. Provides a link between the idea of movement and the motor expression of that idea |
When does neuronal activity of the basal ganglia occur? | BEFORE a particular movement begins |
What do lesions of the basal ganglia cause? | disturbances in the initiation or cessation of a motor event. |
What do disturbances in the function of the descending pathway result in? | paralysis or paresis |
How do neuronal circuits within the basal ganglia put together sequences of movements? | thru reverberating loops between thenuclei |
Where are the movements of the basal ganglia seen? | handwriting, walking facial expression, a lay up…more complex, hierarchically organized sequences |
What are the 3 nuclei of the basal ganglia? | caudate nucleus, putamen and globus pallidus |
What are the nuclei of the basal ganglia also called? | corpus striatum |
What forms the lentiform nucleus? | the putanem and globus pallidus |
What is the neostriatum? | caudate nucleus and putamen |
What nuclei are closely associated with the basal ganglia? | substantia nigra and subthalamic nucleus |
How is the globus pallidus divided? | medial and lateral (GPm and GPl) |
What are the 2 neoronal inputs to the basal ganglia? | corticostriatal fibers and substania nigra |
What is the substantia nigra ? | midbrain structure that arises form dopaminergic neurons and deliver dopamine |
What is the effect of dopamine on neurons? | varies depending on the neuron |
What is the effect of dopamine on D1 receptors? | excitatory |
What is the effect of dopamine on D2 receptors? | inhibitory |
What are the neural outputs from the basal ganglia? | from the GPm to the ventral lateral and ventral anterior nuclei of the thalamus which then project to the cerebral cortex |
Where are corticostriatal fibers projecting from and why is that important? | pyramidal cells and use glutamate so it will increase the firing of the post-synaptic neurons |
What will activating an inhibitory neuron do? | decrease the activity of the following excitatory neuron and decrease exitoatory input to the end target |
What will inhibit an inhibitory neuron do? | reduce activity of the first inhibitory neuron and will reduce the activity of the following inhibitory neuron and will release the end target from inhibition. |
What is disinhibition? | inhibiting an inhibiting neuron |
What are the symptoms parkinson’s disease? | akinesia, bradykinesia, rididity, tramor at rest |
What is the pathology of Parkinson’s? | loss of dopaminergic neurons of the SN that project to the neostriatum. This disinhibits the indirect pathway and removes a source of activation of the direct pathway |
What are the symptoms of Ballismus? | violent flinging movement occurring in a proximal musculature |
What is Ballismus? | disorder that is the result of damage to the subthalamic nucleus, that modulates basal ganglia output thru the pallidum and nigra. Part of the indirect pathway-. lesions of the subthalamic nucleus would lead to increased motor output |
What is huntington’s chorea? | genetic disorder that is progressive. It is a loss of cells in striatum that give rise to indirect pathways. Result is increased motor output from cerebral cortex with accompanying hyperkinetic disburbance. Looks like a robotic movement |
What is the limbic Loop? | neuronal circuit that connects the nucleus accumbens to the basal ganglia. Involved with giving motor expressions to emotions and is rich in dopamine neuron endings. |
What is bradykinesia, hypokinesia? | slowed movements |
What is rigidity? | resistance to passive movements |
What is dystonia? | sustained abnormal distorted positions |
What is athetosis? | twisting, writhing limb movements |
What is chorea? | continuous involuntary movemtns |
What is ballismus? | flinging movements of the limbs |
What are tics? | brief action preceded by urge and followed by relief |
What is myoclonus? | sudden muscular jerk |
What is tremor? | rhytmic semirhythemic oscillating movements |